Blame view

ffmpeg-4.2.2/libavformat/vc1dec.c 2.69 KB
aac5773f   hucm   功能基本完成,接口待打磨
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
  /*
   * VC-1 demuxer
   * Copyright (c) 2015 Carl Eugen Hoyos
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with FFmpeg; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #include "avformat.h"
  #include "rawdec.h"
  #include "libavutil/intreadwrite.h"
  #include "libavcodec/vc1_common.h"
  
  static int vc1_probe(const AVProbeData *p)
  {
      int seq = 0, entry = 0, invalid = 0, frame = 0, i;
  
      for (i = 0; i < p->buf_size + 5; i++) {
          uint32_t code = AV_RB32(p->buf + i);
          if ((code & 0xffffffe0) == 0x100) {
              int type = code & 0x11f;
              i += 4;
              switch (type) {
              case VC1_CODE_SEQHDR: {
                  int profile, level, chromaformat;
                  profile = (p->buf[i] & 0xc0) >> 6;
                  if (profile != PROFILE_ADVANCED) {
                      seq = 0;
                      invalid++;
                      continue;
                  }
                  level = (p->buf[i] & 0x38) >> 3;
                  if (level >= 5) {
                      seq = 0;
                      invalid++;
                      continue;
                  }
                  chromaformat = (p->buf[i] & 0x6) >> 1;
                  if (chromaformat != 1) {
                      seq = 0;
                      invalid++;
                      continue;
                  }
                  seq++;
                  i += 6;
                  break;
              }
              case VC1_CODE_ENTRYPOINT:
                  if (!seq) {
                      invalid++;
                      continue;
                  }
                  entry++;
                  i += 2;
                  break;
              case VC1_CODE_FRAME:
              case VC1_CODE_FIELD:
              case VC1_CODE_SLICE:
                  if (seq && entry)
                      frame++;
                  break;
              }
          }
      }
  
      if (frame > 1 && frame >> 1 > invalid)
          return AVPROBE_SCORE_EXTENSION / 2 + 1;
      if (frame >= 1)
          return AVPROBE_SCORE_EXTENSION / 4;
      return 0;
  }
  
  FF_DEF_RAWVIDEO_DEMUXER2(vc1, "raw VC-1", vc1_probe, "vc1", AV_CODEC_ID_VC1, AVFMT_GENERIC_INDEX|AVFMT_NOTIMESTAMPS)